1. Technical Field
The present invention relates to a water-based rust preventive pigment having high storing stability underwater, a water-based rust preventive paint having the water-based rust preventive pigment, and a highly corrosion resistant surface-treated chain, such as a bushing chain and a roller chain, which is used under a corrosive atmosphere of salt water, acid, and alkali.
2. Description of Related Art
As a conventional rustproof agent for an iron surface, a rust preventive paint containing zinc and aluminum as metal pigments is widely used, utilizing sacrificial corrosion preventive actions of zinc and aluminum (the action of suppressing corrosion of iron by these metals eluted before elution of iron because these metals have an ionization tendency higher than that of iron).
Since such metal pigments react with water and corrode, they have low storing stability in a water-based paint. Therefore, there is a problem that the property of the water-based rust preventive paint blended with the metal pigments is damaged with time.
Japanese Patent Application Laid-Open No. 11-323181 discloses an invention of a water-based paint having a metal pigment, made by coating a metal powder with an organosulfur compound to make a metal pigment and blending the metal pigment, in order to improve the storing stability.
Further, a conventional corrosion resistant surface-treated chain used under a corrosive atmosphere of salt water, acid, and alkali is produced by assembling a chain with a connection pin, a bushing, an outer link plate, an inner link plate, and a roller, which are chain component parts, and then subjecting the chain to corrosion preventive processing such as nickel plating, zinc plating, and dacrotized coating.
In the conventional corrosion resistant surface-treated chain, in a case that a plating treatment liquid has not sufficiently permeated into the inter-spaces between the connection pin and the bushing, and between the bushing and the roller, internally propagating corrosion in a hole shape, which is generally called “pitting corrosion”, cannot be completely suppressed. Further, the chain may be fatigued and broken when it is used under external load environment. Furthermore, when the plating treatment liquid is remained excessively in the inter-spaces between the connection pin and the bushing, and between the bushing and the roller, these members may be adhered to each other so as to cause bending failure of the chain or roller rotation failure.
In order to solve these problems, Japanese Patent Application Laid-Open No. 7-127692 discloses a corrosion resistant surface-treated chain produced by subjecting a connection pin, a bushing, an outer link plate, an inner link plate, and a roller, which are chain component parts, to corrosion preventive processing such as nickel plating, zinc plating, and dacrotized coating before assembling the chain, so as to prevent shortening of the life of the chain due to corrosion. Japanese Patent No. 3122037 discloses a corrosion resistant surface-treated chain produced by forming a zinc layer on a chain component part before assembling the chain, and forming a coating film on the zinc layer using a paint containing an aluminum powder and a silicone resin, so as to prevent generation of white rust on the surface of the chain component part. Japanese Patent Application Laid-Open No. 61-67773 discloses a corrosion resistant surface-treated chain produced by adhering a zinc alloy to the chain component parts before assembling the chain, and subjecting the surfaces of these parts to a chromate treatment.